The present invention relates to a sensor mounting structure for mounting an automotive sensor (e.g., a pressure sensor, a temperature sensor, etc.) and a semiconductor pressure sensor to be used.
There have been used various kinds of sensors for electronically controlling an internal-combustion engine mounted in a motor vehicle. These conventional sensors were attached by screws. For instance, as disclosed in Japanese Unexamined Patent Publication No. Hei 5-172673, brackets are attached in two places on a plastic molding housing to provide the pressure sensor mounting position with a degree of freedom of movement. The pressure sensor is attached by screws in an appropriate position through the bracket and the sensor section and a pressure source are connected by means of a hose.
In recent years, a metal intake air passage, or a so-called intake manifold made of a metal, for use in the internal-combustion engine in motor vehicles is giving way to an intake manifold of synthetic resin. In the case of the synthetic resin manifold, it becomes necessary to form, by insert-molding, a metal part for receiving a mounting screw to fix a sensor housing at the time of molding the intake manifold, resulting in an increased cost.
It is also necessary to insert a metal bushing on the housing side to prevent biting and loosening of the screw, which also increases the cost.
To facilitate the mounting of the sensor, therefore, there has been proposed a method of dispensing with a bracket and a hose for introducing the pressure from the pressure source, and fixing the sensor directly on the pipe wall of the intake air passage in place of using the screw.
For instance, according to Japanese Unexamined Patent Publication No. Sho 63-215847, a cylindrical section larger in diameter than the sensor body is employed as the sensor mounting section. On the sensor side is provided a locking flange section of a non-circular contour; and an insertion hole is formed in the cylindrical section to insert the sensor. The insertion hole has a locking hole for inserting the locking flange portion of the sensor at a specific angle in the inlet side and, after insertion, the locking flange section is allowed to turn. The locking flange section of the sensor is locked by a spring force on the inside surface of the locking hole to thereby mount the sensor.
This method, however, requires insertion of a spring member beside the sensor body into the sensor mounting section (cylindrical section), which will increase both cost and labor for assembling.
In Japanese Unexamined Patent Publication No. Sho 63-215846, disclosed is the sensor mounting structure that a cylindrical portion is provided as a sensor mounting section which is larger than the sensor body; on either one of the cylindrical portion and the sensor, there is provided an elastic locking leg which is elastically deformable in the radial direction of the cylindrical portion; on the other, a fixed locking portion is provided to lock and lock the sensor from turning in engagement with the elastic locking leg in a free state; and the elastic locking leg is pressed into contact with the fixed locking portion by the force of a disk spring, to thereby prevent accidental removal of the sensor. In this case also, it becomes necessary to form a cylindrical portion as the sensor mounting section, and to insert a spring member beside the sensor body into the sensor mounting section (cylindrical portion), resulting in an increased cost and labor for assembling.
In Japanese Unexamined Patent Publication No. Hei 10-122914 there has been proposed a sensor mounting structure in which an elastic member (e.g., a rubber member) having a front end flange and a rear end flange is attached on the projecting portion of a sensor; the elastic member together with the projecting portion of the sensor is inserted, with the rear end flange left non-inserted, into a through hole provided in a member to be attached. After insertion, the front end flange is locked on the inside surface of the member to be attached, while the rear end flange is locked on the outside surface of the member to be attached. The example given above requires an elastic member for mounting the sensor, which increases the number of component parts, and furthermore requires a process for mounting the elastic member to the projecting portion of the sensor prior to mounting the sensor.
It is, therefore, an object of the present invention first to provide a sensor mounting structure for motor vehicles which facilitates mounting the sensor to the wall of the intake manifold while dispensing with screwing of the sensor, and further to decrease the number of component parts and to simplify the structure as compared with a conventional mounting structure system which needs no screws.
It is another object to provide a semiconductor pressure sensor capable of directly mounting an intake air pressure sensor which is one of automotive sensors, to the wall of the intake manifold, and installing the pressure detecting gauge of the sensor into the intake passage while dispensing with a pressure inlet pipe.
It is further another object to provide a sensor mounting structure capable of preventing water formed by condensation from icing in the pressure detecting section to maintain reliability of the pressure detecting section when the semiconductor pressure sensor is mounted directly on the wall of the intake manifold, particularly when the semiconductor pressure sensor is mounted with the pressure inlet port in a horizontal or nearly horizontal position.
To accomplish the above-described objects, the sensor mounting structure for motor vehicles of the present invention has basically the following configuration.
According to the first invention, in the sensor mounting structure for motor vehicles for mounting, on a wall section of a part to be detected, a sensor for detecting a physical value necessary for operating a motor vehicle, characterized in that said sensor is mounted by: providing a sensor mounting hole of non-circular contour for inserting a part of said sensor into said wall section of said part to be detected; and forming in a housing of said sensor, integrally with said housing by molding, first locking portion allowed said sensor to insert into said mounting hole in a specific orientation and engaged on the wall surface which faces the inside of the part to be detected by turning through a specific angle after insertion, and second locking portion engaged on the wall surface which faces the outside of the part to be detected ; and holding said wall section of said part to be detected between said first and second locking portions.
According to the above-described configuration, when the sensor is attached on the wall section of a part to be detected, the first locking portion provided on the sensor housing is directed to a specific orientation, aligning both the first locking portion and the mounting holes made in the wall section of the part to detected. In this state, the sensor housing is inserted into the mounting holes thus aligned (until the first locking portion passes through the outlet of the mounting hole, or, in other words, until the second locking portion contacts the wall surface which faces the outside of the part to be detected). Thereafter, as the sensor housing is turned through a specific angle, the first locking portion is engaged on the wall surface which faces the inside of the part to be detected, while the second locking portion is engaged on the wall surface which faces the outside of the part to be detected. The first and second locking portions hold the wall section of the part to be detected, thus directly mounting the sensor on the wall section of the part to be detected, without using the screw.
According to the second invention, a housing making up a sensor body is formed to be attached on the wall section of the part to be detected, with a gauge portion thereof disposed directly on the part to be detected, and is of a two-piece structure which includes a sensor holder having a pressure detecting semiconductor gauge housing section, a housing section for holding a circuit substrate mounted with an electronic circuitry and a connector, and a cylindrical cap in which the sensor holder is inserted, with the connector mounted outside; and a pressure inlet port is formed by the shape of semiconductor gauge housing section of the sensor holder and the cap.
According to the above-described configuration, the sensor body (sensor housing) is formed simply by inserting the sensor holder having an electronic circuit section and a semiconductor gauge into the cap with the connector portion left outside, and the semiconductor gauge ( pressure detector) housing section is located in the pressure inlet port, thereby enabling direct detection of a pressure without a pressure inlet pipe. Besides, the semiconductor gauge, if disposed directly into the part to be detected (e.g., the intake manifold), is protected by the cap positioned around the gauge, to thereby insure reliability of the pressure sensor.
In the sensor mounting structure for motor vehicles according to the third invention, the pressure sensor is attached directly on the intake manifold of the internal-combustion engine through the mounting hole provided in the pipe wall of the intake manifold; and the pressure inlet port of the sensor opens directly into the intake manifold. A gauge which responds to the pressure is mounted in this pressure inlet port.
In this sensor mounting structure, the pressure inlet port of the pressure sensor is mounted horizontally or nearly horizontally; in this mounting state, the gauge is disposed in the upper part of the inside of the pressure inlet port.
In the configuration in which the pressure sensor is mounted directly on the pipe wall of the intake manifold with the pressure detector (gauge portion) exposed into the intake manifold, the pressure sensor has such a drawback that if the pressure inlet port is located horizontally or nearly horizontally, water generated as a result of sweating in the intake manifold enters the pressure inlet port and freezes to give damage to the gauge. However, when the gauge is disposed in the upper part of the pressure inlet port as stated in the above-described configuration, water caused by sweating will not enter the gauge. It is, therefore, possible to protect the gauge from damage resulting from icing.